Voltage regulator



March 22, 1938.

Filed Sept. 5, 1935 MWW E F117- 2. X s s E h.

WITNESSES: 0 INVENTOR me 0 5e fi rye C. Hrmsfrovy.

Patented Mar. 22, 1938 PATENT OFFEC VOLTAGE REGULATOR,

George 0. Armstrong, Forest Hills, Fa, assignor.

to Westinghouse Electric 85 Manufacturing Company, East Pittsburgh, Pa, a corporation of Pennsylvania Application September 5, recs. Serial No. se,%t

3 Claims.

This invention relates to voltage regulators.

It is an object of this invention to provide a voltage regulator of more dead-beat action than has heretofore been obtained.

It is a further object of this invention to produce a voltageregulator thoroughly reliable and of less cost than those heretofore known.

Other objects of the invention will be apparent from the following description and the accompanying drawing, in which:

Figure 1 is a diagram illustrating the voltage regulator and its circuit; and

Fig. 2 is a set of curves used in the explanation of the invention.

In Fig. 1, the line I supplies direct-current power which is intended to produce a uniform alternatingcurrent voltage on the line 2-2. The voltage is supplied by means of an alternating-current generator 3 having a field t and driven by a motorfed from the line I. Connected across the line 2 is the voltage regulator which comprises a magnetic circuit 5 having two branches. One branch has less iron than the other. This is represented in the drawing by a notch 6, although in actual construction, a small.- er body of iron in this branch than in the other branch could be used;

The middle member I of the magnetic circuit affords a pole face on which arotor 8 moves. On

the branch having the smaller amount of iron is a coil 9. The number of turns in this coil is preferably larger than that of the cell It on the other branch. Instead of the larger mimber of turns, I may obtain the same effect by altering the length of the branch or of the air gap therein.

In series with the coil 8 is an adjustable resistor II and an adjustable resistor i2 may be in series with the coil Ill. The connections through the coils and resistors in each case are across the line 2.

\ The rotor 8 is mounted on the pole face i to oscillate under the influence of the alternating flux of. the pole faces l3 and H inthe two branches, respectively. The windings of the coils 8 and Ill are in such senses that the polarities of poles l3 and I l at any one moment are alike. Springs I5 and I6 act on the rotor' 8 through pressure blocks. A spiral spring I! connects the I rotor 8 with a shaft l8 which may be mounted in any suitable bearings. Springs l8 and 20 serve to center the arm 2| which is connected to the shaft l8. Contacts 22 and 28 cooperate with contacts 24 upon said arm. I

Contact 24 is connected to one side or the line (Cl. ris -s35) l contacts 22 and 28 are connected, respectively, to fields 5 and of a motor 2?. The armature of this motor is connected between that side of the line H which is not connected to the contact 2t and the common terminal of the two fields 25 and it. The motor drives an adjustable rheostat fit. which is connected in series between the held t and the line 6.

In operation of the device, at low voltage, the coil iii will produce less flux in the branch having the pole face it than the coil 5 will produce in the branch having the pole piece it. At higher voltage, the efiect oi the notch 6 becomes noticeable and the coil Si produces less flux through the pole it than the coil ill produces through the pole it.

This is illustrated in Fig. 2 where the curve Al3 shows the flux in pole l3 and the curve B that in pole it for given voltage across the line 2. These curves cross one another because for the magnetic circuit with the smaller amount of iron, the increase in flux with increasing voltageis more rapid at low voltage than it is at higher. For the magnetic circuit with the more iron and the fewer turns in the coil, the increase in flux with increasing voltage is less rapid at low voltage and more rapid at high voltage than with the other magnetic circuit. This means that the curve Alt will be steeper at first than curve B but more nearly horizontal at high voltage than curve Bit. The two curves must, therefore, cross. The resistor M is adjusted so that the fluxes through the two pole faces are equal at the voltage on the line 2 which is desired. The resistor l2, if one is used, is so adjusted that the adjustment just described can be accomplished with a convenient setting of the resistor H.

When the flux in the two branches is equal the device is without effect upon the rotor 8. When the flux through the branch H is greater than the flux; through the branch l3, the rotor 8 is subjected to the flux entering from the pole face I and to the difference between the flux from pole l3 and that from pole M. It is also subjected to the biasing effect of one of the springs l5 and I8 and its action is further eflected by its bwn hysteresis. The combined effect of these three influences has been discussed in detail in my copending application Serial No. 46,287, flied October 23, 1935.

When the attraction of pole ll exceeds that of pole H, the motion of the rotor 8 will result in a cumulative, eflect of a. rotation clockwise as seen. in Fig. 1. The step-by-step character of this rowh ch is largely absorbed by theactionof the spring II, the individual steps or the rotation being too rapid to show in the movement oi. the cylinder U. The moment of inertia of the arm 2| is great enough to further absorb what remains of the non-uniform characteristic of the rotation and the result is that the arm moves toward the right with a practically steady torque. This brings the contact 24 against the contact 23 and holds it there. After the motion of the arm 2| is stopped by the contacts being in engagement, further motion of the rotor 0 is absorbed in tightening the spring ll until this spring exerts enough biasing effect to prevent further rotation of the cylinder.

When the tractive effect of the pole I3 exceeds that of the pole I4, a similar action takes place in the opposite direction. The spring It then takes the place of the spring l6 and the spring I9 that of the spring 20. The contact 24 in this case meets the contact 22.

When the voltage on the line 2 is low, current in coil 9 produces more flux in pole l3 than current in coil III produces in pole l4. It results, therefore, that contacts 22 and 24 close with the result that the field 25 and the armature 21 are connected as a series motor and the rheostat 28 moves to adjust the field 4 so that-the voltage will be corrected.

On the other hand, when the voltage on the line 2 is high, the rotor 8 will move clockwise as seen in Fig. 1, and contacts 24 and 23 will close, with the result that the field 28 now cooperates with the armature 21 and the rheostat 28 is moved in the opposite direction adjusting the field 4 in the opposite way, to'again correct the voltage on the line 2.

Many modifications o! the details of this invention will be apparent to those skilled in the art and I do not wish to be limited by the specific i1- lustration 01' one circuit.

I claim as my invention:

1. A magnetic structure having a central portion and two side portions of diflerent reluctance, a coil on each of the two side portions, an adjustable resistor in series with one coil, a pole on the central portion and a pole on each side portion, the three poles being adjacent each other, a hollow cylinder of magnetic material in the space separating said poles said cylinder resting on the pole of the central portion, and spring-pressed blocks acting on said cylinder from each side, whereby the cylinder will rotate, under the influence of said pressure, the friction with the pole face and the difference between the fiux in the two side portions, in one sense or the other according as the fiux in one side portion or the other is greater.

2. In a voltage regulator, a magnetic structure having two portions oi different reluctance provided with pole faces and a member common to both of said portions, coil means for energizing said portions, a cylinder of magnetic material in the space between said pole faces and contacting said common member, spring-pressed blocks acting on said cylinder from each side, whereby the cylinder will rotate under the infiuence of said pressure and the diflerence between the fiux in said two portions, in one direction or the other according as the fiux in one portion or the other is greater, and contact-making means controlled by said rotation.

3. In a voltage responsive device, a magnetic circuit having two branches severally comprising portions extending in substantial alinement and a member common to both of said branches and extending at substantially right angles to said portions, coil means for separately energizing each 01 said branches, one of said coil means having more turns than the other, and a member rotatable in response to the relative fluxes from both of said coils around an axis at substantially right angles to the fiux emanating from each of said portions and from said common member, one of said branches having less iron than the other and having wound thereon said coil having more turns, whereby the effect of one branch on said rotatable member increases with increasing voltage faster at low voltage and slower at high voltage than the ei'fect of the other.

GEORGE C. ARMSTRONG. 

